Installing a Solar Array
Steps to Install or Upgrade a Solar Array
1. Review the DER Interconnection Handbook
Read the Distributed Energy Resources (DER) Handbook. This handbook explains what you need to connect your solar, battery storage, or other power system to City Light's electrical grid.
2. Submit Your Application
Submit your online application. Include these items:
- One-line and riser diagrams.
- Inverter and module specifications.
- A site plan.
You can also submit a completed and signed Interconnection Agreement (Level 1-2 Interconnection Agreement and Level 3-4 Interconnection Agreement) now or wait to receive one from City Light (see Step 4). If you need extra service work, you must submit a separate application.
3. Engineering Review
We may require an engineering review for:
- Systems larger than 12 kW (AC).
- Systems with battery backup.
- Systems located in the network areas of: Downtown, First Hill, South Lake Union, and University District.
- A transformer upgrade and/or extra distribution work.
These projects may require protective equipment and take more time, costs, and coordination.
4. Interconnection Agreement
If you did not submit your interconnection agreement with your service application, we will send you instructions. You will need to return the signed agreement through Adobe Sign after we review and approve your application. City Light will sign and return a completed copy to you.
5. Permission to Construct
Once we receive your signed Interconnection Agreement, your Electrical Service Representative (ESR) or Electric Service Engineer (ESE) will send you a Permission to Construct (PTC) letter. Do not begin installation until you receive the PTC letter.
6. Commissioning and Testing Attestation Form
Your ESR or ESE will provide a Commissioning and Testing Attestation form. Complete and sign this form. You will submit it in Step 7.
7. Electric Permit and Inspection
Get permits through your local permitting jurisdiction.
After your system passes inspection by the Authority Having Jurisdiction, email us at SCL_SolarRequest@seattle.gov.
Attach these items in your email:
- Proof of passed final inspection.
- Completed and signed Commissioning & Testing Attestation form.
8. Utility Inspection
Your ESR or ESE will inspect your installation. We will confirm it meets City Light Requirements and Standards.
9. Billing
We will bill any applicable fees to the party listed as responsible for construction charges on the Electric Service Application. You can pay by phone, in person, or by mail.
10. Permission to Operate
Once all inspections pass and we receive all required payments, your ESR or ESE will issue a Permission to Operate (PTO) letter to the Primary Contact listed on the application. Your system cannot be energized or operated until you receive your PTO.
Solar Installation Frequently Asked Questions (FAQs)
City Light Engineering reviews all applications over 12 kW. We check if your system may affect the distribution system. We review for the following:
- Equipment is compliant with UL and IEEE standards.
- Exportation of energy does not overload the transformer, eeder line or service line.
- There is a clear AC disconnect for all generation sources.
Yes. All installations must meet the requirements in the Distributed Energy Resources (DER) Interconnection Handbook. The location of the interconnection meter socket must meet all current requirements for access and placement. See Requirements for Electric Service Connection (RESC) - Chapter 6 Metering.
The Electrical Service Representative (ESR) or Electric Service Engineer (ESE) inspects to ensure compliance with City Light Requirements and Standards. When planning your installation, pay close attention to the Requirements for Electric Service Connection (RESC) - City Light 1554.33 Meter Mounting Configurations, Heights, Working Space, and Clearances, Exterior (Outdoor).
City Light no longer installs Solar Production Meters. You may choose to install a customer-owned production meter. However, any production meter must be outside of the Meter Working Area. See Requirements for Electric Service Connection (RESC) - City Light 1554.33 Meter Mounting Configurations, Heights, Working Space, and Clearances, Exterior (Outdoor). You must install a Phenolic Label on the production meter to confirm that it is customer-owned. If you install a production meter for an existing solar system, you do not need to submit a service application. This is because City Light does not track production meters. You must submit a service application when:
- A ”meter pull” is required.
- Installing a production meter for an existing solar system changes existing City Light equipment.
You may contact SCL_SolarRequest@seattle.gov with questions in this situation. If a production meter is installed with a new solar system, this is covered by the service application submitted for the new solar system.
You are responsible for the cost of any electrical system upgrades required solely due to the solar installation. If the upgrade would not be needed otherwise, the customer must pay for it.
These costs may include but are not limited to:
- Upgrading the service conductor from the serving facility to your service termination point.
- Upgrading service conductors for other customers or neighbors if their service is affected.
- Making permanent connections on service conductors.
- Inspecting and resealing the meter.
- Other related work required to safely interconnect the system.
These are some of the most common costs associated with solar installation. This list is not all-inclusive. More upgrades may be required and will be evaluated on a case-by-case basis.
No. Net Metering isn’t available in the network. A customer cannot get credits for exporting power to the grid because exporting power to the grid is not permitted in the following areas: most of Downtown Seattle, and parts of First Hill, South Lake Union, and the University District. See Distributed Energy Resources (DER) Interconnection Handbook - Sections 7.2 and 17.
Customers who have opted out of Advanced Metering may not interconnect to City Light’s distribution system. Opt-out meters can be identified by a blue stripe on the face of the meter.
If you would like to opt-in to Advanced Metering, contact your ESR at SCL_SolarRequest@seattle.gov.
The Level 1-2 Interconnection Agreement and Level 3-4 Interconnection Agreement are available on our website. The website also has guidance on which agreement applies to each project type. Solar installers or customers may download the appropriate agreement and submit it with the Electric Service Application for review.
You may complete the required fields, but do not sign the agreement if you submit it with the application. After the ESR or ESE reviews and approves the application, we will send the agreement for signature through Adobe Sign to the party listed on the agreement.
The customer signs the interconnection agreement.
The new interconnection agreements replace the prior versions. Use the current versions, Level 1-2 Interconnection Agreement or Level 3-4 Interconnection Agreement.
The Commissioning and Testing form confirms that your proposed DER meets all applicable configuration, licensure and permits, and safety requirements.
You sign the form to certify that the proposed DER fully meets utility interconnection requirements. You agree not to turn on your proposed DER until you receive a Permission to Operate (PTO) letter from City Light.
We will send the form at the appropriate time for signature. It is not available on our website.
This period of energization for testing or inspections should be minimal. The system must not be permanently energized until City Light has issued a Permission to Operate (PTO) letter.
You will not be credited for export (net metering or large renewables) prior to the date we issue the PTO.
Expanded systems must meet the requirements in the City Light Distributed Energy Resources (DER) Interconnection Handbook and Requirements for Electric Service Connection (RESC) - City Light 1554.33 Meter Mounting Configurations, Heights, Working Space, and Clearances, Exterior (Outdoor).
We will require a new or modified interconnection agreement and one-line diagram.
See the Distributed Energy Resources (DER) Interconnection Handbook - Section 14.7.2 and your interconnection agreement (Level 1-2 Interconnection Agreement or Level 3-4 Interconnection Agreement). When a solar array is decommissioned, the property owner is responsible for notifying City Light at SCL_SolarRequest@seattle.gov.